Process of making sulfuric acid



E. L. LARISON.

PROCESS oF MAKING suLFuRlc ACID.

APPLICATION -FILED AUG.25 I9I9 1,342,024.

Patented June 1, 1920.

2 SHEETS-SHEET I l rf.

E. L. LARISON.

PROCESS 0F MAKING SULFURIC ACID.

. APPLICATIQN FILED A.UG.25| I919.

Patented June 1, 1920.

2 SHEET? -SHEET 2.

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SMM/M4436 ybeen customar PATENT OFFICE.

` ELDON' L. LARISON, 0F ANACONDA., MONTANA.

Specification of Letters Patent. Patented June 1, 192,0.

Application filed August 25, 1919. Serial No. 319.607.,

To ali/whom it may concern:

Be 1t known that I, ELDoN L. LARIsoN, a cltizen of the United States, residing at Anaconda, in the countyof Deerlodge and State of Montana, have invented certain new and useful Improvements in Processes of Making Sulfuric Acid, of which the following is a specification.

In the manufacture of sulfuric acidby the so-called chamber process, involving reactions between sulfur dioxid, oxids of nitrogen, oxygen and water, it has heretofore to employ reaction chambers of lead. ead has been used almost exclusively for this urpose because it is relatively cheap, it e ectively resists the chemical action of the original reagents and intermediate and final reaction products, and

finally because it is a good conductor of heat.4

The heat-conductivity of lead is an important factor in its use, because the acid-forming reactions generate a large amount of heat, and the ability to remove the excess heat of reaction is a limiting factor in the capacity of a set of lead chambers. In the usual lead chamber construction .the excess heat must be dissipated by radiation, and since the radiating capacity of the chambers is practicallyva fixed quantity and cannot be varied at will, a rather definite limit of production is set beyond which the chambers fail to function properly.

It has long been recognized that the re,- action velocity in the chamber process could be increased by a vigorous mixing of the gases, causing them to impinge upon surfaces wet with acid. Various forms of construction have been used or proposed for use to utilize such effects; but with a construction involving lead as the chief acid-retaining material, the original plant costs and the increased maintenance costs have been such that little or no advantage has been secured as compared with the conventional chamber construction.

.I have discovered a process of making sulfuric acid, without the necessity for lead chambers, whereby the acid making reactions take place with such intensity, rapidity and thoroughness that much greater proportionsof the oxids of nitrogen can be employed than heretofore and many times as much acid produced in'unit time as is at vpresent possible with thelead chamber process.

' In the lead-chamber process as carried out under present practices/the percentage of nitrous gas in the Glover tower mixture is substantially that derived from one part of sodium. nitrate to every four parts of sulfur. In other words, for every four pounds of sulfur in the form of sulfur dioxid as entering the Glover tower, an amount ofg nitrogen compound equivalent to one pound of sodium nitrate is introduced at the top ofthe tower.` This is the established proportion for maximumacid-production. If the proportion of nitrous gas be exceeded to any substantial extent, no increased production of acid results, but increased loss of niter occurs. in ordinary chamber practice results from the fact that when radiation is chiefly depended on vfor temperature control, the temperature ofl the gas mixture inthe first chamber rises too high for roper completion of the cycleof acid forming reactions if substantially more than the above men- ;tioned proportion of niter is used. According to the present invention it is possible to employ from two to four times as much of the nitrogen oxids as can be used in the leadchamber process.

In my process the optimum temperature for. the reactions between the components of the gas mixture, viz. about 90 C., 1s

vmaintained in not only the earlier parts of the packed reaction compartments but to a, great extent in the later parts as well. In the lead chamber process the optimum temperature can lbe maintained to advantagein only the first one or two chambers while 1n the later chambers gradually decreasing and hence less favorable temperatures invarlably exist.

The advantages of the foregoing conditions are obvious.' The acid-forming reactions are accelerated to such an extent that the acid yield is many times that attainable under the bestfchamber' practises. The sulfur dioxid is completely oxidized, and, despite the considerable increase in niter clr- This limitation ofthe use of niter' culated, there is verylittle absolute increase in niter loss, while there is more than a proportional increase in the amount of acid produced. l.

According to the invention, the Glover tower gases containing the increased proportion 'of oxids of nitrogen are passed into chambers constructed of acid-proof masonry and so sub-divided internally by walls or partitions, preferably of the same material, that the gases are directed along an extended tortuous path, in the course oi' which they impinge upon the surfaces of acid-proof blocks, tiles or the like, with which the several compartments are wholly or partially lilled. ptimum acid-making conditions are maintained in the compartments, and to assist `in this,y the heat of reaction is removed by continuous circulation oit sulfuric acid maintained in the chamber at several points in the path of the gases, the temperature .of the circulating acid being controlled means of an external heat-exchanger4 obstructions in their path, partly to the 'factc that much larger. proportions of niter may be used than heretofore, and partly to. the

fact that through the circulation of acid the optimum acid-making temperature is maintained in the packed chamber.

y' Whereas with theusual lead chamber vop eration the production capacity of any given set of chambers is limited by its radiating capacity, there is no such limit with the operation according to the present invention, since.' the excessive heat of reaction in the packed compartment is lremoved byv the circulating acid and the rate of removal' is dependentV only upon the volume of acid, It is therecirculatedl and its temperature. fore possible to greatly intensify the reactions by introducing with the sulfur d ioxid a much larger proportion, as previously stated, of the oxids of nitrogen than can be carried -in the ordinary chambers on account .of the temperature limitations of /the latter. VA further advantage is'that the masonry construction employed is ,cheaper and more permanent than lead, and does not require buildings toA protect it from the' weather.

Suitable lapparatus for carrying out my process is illustrated somewhat diagrammatically in the accompanying drawings, wherein:

Figure 1 is a central longitudinal section throu h a sulfuric acid system, including the over tower, the masonry chambers, and the Gay-Lussac tower, and

Fig. 2 is agfplan view of the same.

ln said drawings, 10 indicates a blower receiving the dust-free gases containing sulfur dioxid, and introducing them into the Glover tower 11, which ma be of standard construction. From the lover tower the gases are delivered to the masonry chamber 12.

l preferably subdivide this chamber, byacid-proof masonry walls 13, into a multiplicity of vertical tower-like compartments 14, which may be substantially rectangular, i

and which communicate alternately at their upper and lower portions, whereby the gases lare directed in a tortuous course indicated by the arrows in Fig. 1. Preferably the subdividing walls 13 are both longitudinally .and transversely placed, the construction illustrated -by way ot example comprising a triple series of compartments, each series consisting of six interconnected compart ments, or eighteen compartments in all. The' compartments 15 adjacent the exit gas flue 16 may be of similar construction tol the others, and may form a part of the general chamber construction; but they perform the functions of the Gay-Lussac tower.

The. acid-circulating system through the Glover and Gay-Lussac towers comprises a Y distributing tank mounted above the Glover tower 11, 'and discharges the acid into the Glover tower through distributing heads 21. The acid flows from'the` tower into the collecting reservoir 22, and is conveyed by circulating pump 23 and ipes 24 tothe distributing reservoir 25A or the Gay-Lussac towers 15. From the collecting reservoir 26 of the Gay-Lussac towers the acid'is returned b circulating pump 27 and pipes 2.8 to the lover tower distributing reservoir 20, thus completing thecircuit.

An independent acid-circulating system is rovided for the masonry chambers'. As illustrated, this comprises a distributing reservoir 30 mounted ,above the compartments 14; `one or morev distributing heads 31 in each compartment; an external heatexchanger illustrated as comprising three water-cooled units 32 for controlling the temperature of the eiliuent acid; and a 'circulating pump' 433 serving to return the cooled acid by pipeY 34 to the distributing reservoir'30. *A

The concentrationof. the circulating acid should be such as to avoid excessive absorpi tion of the compounds of nitrogen, concenitrations aroundfO"v C.being suitable. The -l maintenance ofthe proper concentration iii-' 'V volves the vcontinuous or intermittent dilution of this acid, for example by the supply of water or dilute acid at any appropriate point in the circulating system. A correspondingv volumeof chamber -acid is of course withdrawn from the system at any appropriate point, indicated, for example at 36. The acid should be circulated in such volume and its temperature should be so controlled as to maintain the optimumworkin conditions within the chamber. l

' eans for supplying any desired quantity of chamber acid to the Glover tower are indicated at 37.

The apparatus referred to is not claimed in this application but is the subject of a prior application, Serial No. 254,794, filed eptember 19, 1918, of which thepresent application is a continuation in part.

1. The process of making sulfuric acid, which comprises passing Glover-tower gases containing a mixture of oxids of sulfur and nitrogen substantially in the proportion derived from not less than one pound of sodium nitrate to each two pounds of sulfur, through a refractory-packed reaction-tower, maintaining the optimum acid-making telnperature in the tower by circulation of acid of predetermined temperature, and then passing the sulfuric acid gases into a Gay- Jussac tower.

2. The process of making sulfuric acid, which comprises passing Glover-tower lgases containing a mixture of oxids of sulfur and nitrogen substantially in the proportion derived from not less than one pound ofsodium nitrate to each two pounds of sulfur, through a series of refractory-packed reaction-towers; maintaining the optimum acidmakin temperatures'in the towers by withdrawa of acid from the bottoms of the towers, ad'usting the temperature of the acid ,and mtroducing the latter into the assing the sulfuric acid gases into a Gayms'sac tower.

3. In the process of making sulfuric acid, the steps which consist in introducing into the gases in the Glover tower oxids of nitrogen substantially in the proportion derived from not less than one pound of sodium -nitrate for each two pounds of sulfur as SO2 present in the gas, passing the gas mixture Vso obtained through an' extended course of refractory packing, and controlling the temperature in said course by passing cool acid therethrough.

4. In the process of making sulfuric acid,

the steps which consist in introducing into the gases in the Glover tower oxids of nitrogen substantially in the proportion derived from not less than one pound of sodium' nitrate for each two pounds of sulfur as SO2 present in the gas, passing the gas mixture so obtained through an extended course of refractory packing, and controlling the reunits at the tops thereof to absorb the heat 'of reaction of the acid-making, removing the accumulated reaction-heat from acid withdrawn from the bottoms of the units, diluting the cooled acid to a concentration suiiiciently low to avoid excessive absorption of nitrogen compounds, and re-circulating the cooled and diluted acid.

6. In the process of making sulfuric acid, the steps which consist in introducing into the gases in the Glover tower oxids of nitrogen substantially in the proportion derived from not less than one pound of sodium nitrate for each two pounds of sulfur as SO2 present in the gas, passing the gas mixture so obtained through a series of refractory-packed reaction-units, introducing acid into the units at the tops thereof to absorb the heat of reaction of-the acid-making, removing the accumulated reaction-heat from acid withdrawn from the bottoms of the units, diluting the cooled acid to a concentration suliciently low to avoid` excessive absorption of nitrogen compounds, and recirculating the diluted acid. 7. The process of making sulfuric acid which comprises introducing into the gases in the Glover tower oxids of nitrogen substantially in the proportion derived. from not less than one pound of sodiumvnitrate for each two pounds of sulfur as SO2 present inthe gas, passing the gas mixture so obtained through an extended course of refractory-packing, controlling the temperature in said course by passing cool acid therethrough, and recovering for re-'use the oxids of nitrogen in the eiiuent gas.

8. In the process of making sulfuric acid the packing by circulation therethrough ofacid of regulated temperature.

- l0. In the process of making sulfuric acid,-

'without the use of lead chambers, the steps the steps which consist in introducing into ref`iaetorypeel-ring, and maintaining tIierethega-ses in the Glorer tower oxids ofnitrof 1n a. ,temperature of substantiall not less n substantially inthe proportion derived than 90S C. by circulation theret rough of 1I om not'less than one pound of sodium aoid of regulatedtemperature; 5 nitrate for each-t`wo pounds of sulfuras SO2 In testimony whereof, I aiiix my signature.

present inthe gas, passing the gas mixture j so obtained through 'an extended course of Y Y ELDON L-LA'RISON- 

